public class Example6_4 {
   public static void main(String args[]) {
     CompurerAverage computer;
     double a=11.23,b=22.78;
     computer= new A();
     double result=computer.average(a,b);
     System.out.printf("%5.2f和%5.2f的算数平均值:%5.2f\n",a,b,result);
     computer=new B();
     result=computer.average(a,b);
     System.out.printf("%5.2f和%5.2f的几何平均值:%5.2f",a,b,result);
  }
}
